Let $A$ and $B$ be two sets in the universal set. Then $A - B$ equals

Find the union of each of the following pairs of sets: $A = \{a, e, i, o, u\}$,$B = \{a, b, c\}$.

If $A = \{1, 2, 3, 4\}, B = \{3, 4, 5, 6\}, C = \{5, 6, 7, 8\}$ and $D = \{7, 8, 9, 10\}$,find $B \cup D$.

If $A \subseteq B$,then $A \cup B$ =

Consider the experiment of rolling a die. Let $A$ be the event 'getting a prime number' and $B$ be the event 'getting an odd number'. Write the set representing the event '$A$ or $B$'.

If $A = \{1, 2, 3, 4\}$,$B = \{3, 4, 5, 6\}$,$C = \{5, 6, 7, 8\}$,and $D = \{7, 8, 9, 10\}$,find $A \cup B \cup D$.